Mis soluciones a los cinco ejercicios que no usaban OOP

ex1.rb

prueba = %w(ruby es divertido)

def longitudes arr
  arr.map(&:length)
end

puts longitudes(prueba)

ex2.rb

prueba = "Ruby es el mejor lenguaje porque ruby es el MEJOR"

def histograma paragraph
  paragraph.downcase!
  palabras = paragraph.split(/\s+/)
  frecuencias = {}

  palabras.uniq.each do |palabra|
    frecuencias[palabra] = palabras.count(palabra)
  end

  frecuencias.each do |palabra, frecuencia|
    puts "#{palabra}: #{ '*' * frecuencia}"
  end
end

puts histograma(prueba)

ex3.rb

class Fixnum
  #from http://mitpress.mit.edu/sicp/full-text/book/book-Z-H-11.html#%_sec_1.2
  def prime?
    (1..100).collect do
      a = rand(1 .. self - 1)
      a == expmod(a, self, self)
    end.all?
  end

  private
  def expmod(base, exp, m)
      return 1 if exp.zero?
      if exp.even?
        (expmod(base, exp / 2, m) ** 2) % m
      else
        base * expmod(base, exp - 1, m) % m
      end
  end
end


2.upto(10){ |n| puts "#{n} es primo" if n.prime? }

ex4.rb

def phone_code(phrase)
  keymap = {
    2 => %w(A B C),
    3 => %w(D E F),
    4 => %w(G H I),
    5 => %w(J K L),
    6 => %w(M N O),
    7 => %w(P Q R S),
    8 => %w(T U V),
    9 => %w(W X Y Z),
    0 => [' ']
  }

  phrase.each_char.map do |char|
    char.upcase!
    the_key, the_mapping = keymap.find{|key, mapping| mapping.include?(char) }
    the_key.to_s * (the_mapping.index(char) + 1)
  end.join(" ")
end

puts phone_code("hola mundo la silla y el estante")

ex6.rb

def eval_rpn(exp)
    operations = {}
    %w(+ - * /).each do |operator|
      operations[operator] = ->(a, b){ eval("a #{operator} b") }
    end

    tokens = exp.split /\s+/
    stack = []
    tokens.each do |token|
      unless operations.include?(token)
        stack.push token.to_i
      else
        operands = []
        operation = operations[token]
        operation.arity.times do
          raise "Insufficient operands" if stack.empty?
          operands << stack.pop
        end
        stack.push operation.call *operands
      end
    end

    raise "Unbalanced expression" if stack.size > 1
    stack.pop
end

loop do
   print "RPN> "
   exp = gets.chomp
   puts "=> #{eval_rpn(exp)}"
end